CHAPTER I INTRODUCTION Food fermentation has been in existence since ancient times. Though fermentation was defined in various ways, in simple terms it may be defined as a process for the production of a product by the mass culture of microorganisms (Stanbury, 1995). Fermentation is considered as one of the oldest form of food biotechnology and forms good example for ancient wisdom. Fermentation proved to offer several benefits viz., improves nutritional and sensorial qualities of the substrate thus makes it palatable. The safety of the substrate was reported to be enhanced by fermentation as it reduces toxins and antinutritive factors of the substrate (Gobbetti et al., 1994, Olasupo et al., 1996, Simango, 1997, Nout et al., 1989). In addition recent researches proved biological functions of fermented foods effected due to functional microbes involved during fermentation which provides several health-promoting benefits to the consumers. Thus fermented foods satisfy considerable portion of consumer s nutritional and health needs. Due to nutritional significance and functional importance traditional fermented foods occupy an important place in the diet of people particularly from African and Asian countries (Steinkarus, 1994). Fermented foods are produced by ethnic people using their native knowledge utilising locally available raw materials of plant or animal sources as substrates. The most common substrates used in fermented food preparation include vegetables, bamboo shoot, beans, milk, cereals and millets. The production methodologies of ethnic foods vary according to geographic location and many varieties of fermented foods are available throughout the world. In spite of long practice and nutritional advantages most of ethnic fermented food preparation still remains in homes, villages and few were produced in small scale industries. But the production was done based on traditional knowledge acquired generation to generation. Till 20 th century, research on fermented foods was in its beginning but in recent year s documentation of globally produced fermented foods increased rapidly. The technologies for the industrial production of fermented products from substrates such as milk, meat, fruits, vegetables and cereals are well developed and scientific works are actively carried out all over the world (Hirahara, 1998). Among the fermented substrates, dairy based fermented foods were the most reported ones and 1
some of the dairy fermented foods like yogurt and lassi have received huge market worldwide. Next to dairy foods cereal and millet based fermented foods has historic and scientific importance. Though wide varieties of cereal and millet based fermented preparations are available only very few foods like Ogi, Sourdough and Kenkey have attained technological development. In India several types of fermented foods based on millets and cereals substrates are consumed (Sekar and Mariappan, 2007). Cereal and millet based indigenous preparations of India include non-alcoholic beverages, alcoholic beverages, breads, pancakes and porridges. According to Sekar and Mariappan (2007) Indian fermented foods are prepared with potential knowledge of indigenous people which has due market value. Health benefits of Indian fermented foods have been realised well in recent years due to the documentation of some of the indigenous preparations. However there are many other Indian foods which deserve research and development input as these foods have a major role for millions of people. One of the popularly consumed millet based fermented beverages of south India is Koozh or Ambali (Sekar and Mariappan, 2007). Koozh has strong connection with South Indian culture and tradition and was consumed regularly for breakfast before rice become common consumable. The product is also used as weaning food and has an important role in social functions. The final product is in semi-solid form and the distinct aroma of the product is well appreciated. Also the product is claimed to be healthy and believed to be a complete food. It is full millet based preparation which is fortified with rice and fermented milk just before consumption. Millets like finger millet, pearl millet and sorghum are used singly or in combinations for Koozh preparation. Fermentation process is natural and preparation methodology is unique and different from other documented fermented food preparations as it involves two fermentation processes viz., before (primary) and after cooking (secondary). The processing methodology was similar throughout south India with slight modifications in fortifying substances and raw materials. Traditional koozh preparation method is described in Fig 1.1. 2
Millet of interest grinded to flour Flour mixed in water at the ratio of 2:1 Incubated at room temperature till souring (Primary fermentation (12-15h) Cooked in earthern pot Incubated at room temperature till souring which takes 12-15 h (Secondary fermentation) Fortified with curd and broken rice Koozh Fig 1.1.Flow chart of Koozh preparation in South India Unlike other cereal and millet based fermented foods in which fermenting microorganisms were killed by thermal treatment secondary fermentation step in Koozh offers living microbes along with the product. This feature adds functional value to the traditional product and makes it to stand on par with probiotic dairy foods which are till now widely used food systems for probiotic microbes. Though known from ages, due to urbanization, now Koozh preparation is confined to rural people, agricultural workers and urban poor. The food is occasionally consumed in urban households due to laborious preparation procedures. Recently production of Koozh was taken up as an income generating activity due to the demand as important and cheap meal for daily labourers in cities. According to Tamang et al., (2011) food consumption survey is indispensable tool for assessing the consumption pattern, consumer perception and to analyse limitations of the processing methods. Hence brief survey was conducted with a 3
questionnaire in ten different local production units in Vellore, TamilNadu, India. The raw material used for Koozh preparation is finger millet and in few places pearl millet is also combined. The raw material is purchased on weekly basis. The vendors in cities earn more than Rs. 5000/month while in small towns it varies from Rs. 2000-3000/ month. Eighty percent of consumers were daily labourers and lorry drivers. Some of the vendors reported that few urban people also consume Koozh as it is healthy. Koozh preparation serves as income generation activity for considerable size of population. Some of the consumers were also interviewed. The consumers reported that they consume Koozh because it is cheap and healthy. Further some of the consumers felt that the product gives cooling effect to the body and reduce ill effects of alcohol consumption. The local production units form very good entry points for underutilised yet nutritious millets to urban environment. But the commercial market of koozh did not reach urban people due to some of the limitations. The variations in product quality due to spontaneous fermentation, production of off-flavours due to uncontrolled microbial activity after ripened stage and apprehensions of microbial safety among consumers because of unhygienic practices are the constraints to the expansion as commercial market. Also the product produced in local production units has very poor shelf life. Despite its importance in the diet of large groups of population and necessity for improving the traditional process only few works on primary fermentation of koozh have been published. First report on Koozh fermentation identified five predominant lactic acid bacteria during primary fermentation by conventional identification techniques (Antony and Chandra, 1996). Following this inhibition of pathogenic microorganisms during primary fermentation was reported by Antony et al., (1997). Recently Satishkumar et al., (2010) isolated lactic acid bacteria from Koozh samples and based on the antimicrobial properties only single isolate has been identified. But the results of the study presented Koozh as a potential source of probiotic organisms. Considering functional potential of traditional food and need for scientific attention this study was conducted with the aim to investigate microbial and biochemical changes during Koozh fermentation and to standardize the process. 4
The objectives of the study include 1. To assess microbial, biochemical and sensory changes during primary processing/ fermentation of finger millet, pearl millet, sorghum and maize 2. To assess microbial and biochemical changes during secondary fermentation of finger millet 3. To isolate and characterise predominant microbes involved in primary and secondary fermentation of finger millet 4. To screen the isolates for functional use as starter cultures 5. To standardise the process by employing selected starter cultures. 5